Work-clamp for buttonhole sewing machines



'l1g. 28, 1934. A, R, WOOD 1,971,363

WORK CLAMP FOR BUTTONHOLE SEWING MACHINES Filed Dec. 4, 1951 3 Sheets-Sheet l @i Q ww. m wm Q A wv .wv T-.-.MHWWHHHNHUHHHIVLWHHHww Aug. 28, 1934. A. R. WOOD woRx CLAMP FOR BUTToNHoLE SEWING MACHINES Filed Dec. 4, 1931 3 Sheets-Sheet 2 3 Sheets-Sheet 3 m w, v M im 3 o wm hw wm, um wm, o R T, 1W d llh? -E T ..l-- l. or. .11 A w n m ww Q hm mw m J Aug. 28, 1934. A. R. woon woRK CLAMP FOR BUTToNHoLE SEWING MACHINES Filed Deo. 4, 1931 mw ww um mw i Patented Aug. 28, 1934 PArNr rait;

WORK-CLAMP FOR U'r'roNHoLs SEWING MAoHINEs Alfred R. Wood, Bridgeport,` Conn., assigner to The Singer Manufacturing Company, Elizabeth, N. J., a corporation of New Jersey Application December 4, 1931, Serial No. 578,968

7 Claims.

rIhis invention relates to buttonhole sewing machines more particularly of the type disclosed in the patents to Allen No. 1,35,704, of Nov. 30, 192), and No. 1,777,066, of Sept. 30, 1930.

In machines of the type in question there is a work-clamp comprising lower work-supporting plates and upper work-clamping feet which support and clamp the work entirely around the area of the work to be stitched; the lower work-supporting plates being apertured to expose such area of the work from below and admit the usual needle-throat member or button which is carried by the turret-support for the under-thread mechanism of the machine and supports the exposed area of the workV against the thrust of the usual reciprocating needle. y

These machines also-have a buttonhole-cutter which. cuts a hole in the exposed portion of the work in the work-clamp either before or after the buttonhole has been stitched. To prevent interference between the buttonhole-cutter and the under-thread mechanism and needle-throat member, it has been proposed to relatively separate the work-clamp and needle-throat member vertically to remove the needle-throat member from the level of the lower work-clamping plates and then relatively separate the work-clamp and needle-throat member horizontally to get the needle-throat member out of the way of the advancing buttonhole-cutter.

The relative motions above described have been accomplished by providing means for tilting the entire work-clamp upwardly about its rear end as a fulcrum and by bodily shifting the workclamp rearwardly; such motions of the workclamp operating to lift the lower clamping plates clear of the needle-throat member so that they may be shifted horizontally without clashing with the needle-throat member.

To avoid the necessity of lifting the entire workclamp which entails considerable mechanism, I have provided the present machine with a workclamp the lower plates of which have inset sections which are tiltable upwardly to clear the needle-throat member without the necessity of disturbing the entire work-clamp. By adopting this expedient a simplified operating mechanism may be used and other advantages gained as will hereinafter` appear;

Theinvention further comprises the devices, combinations and `arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention iromwhich the features of the in- Vention and the advantages attained thereby will (Cl. 112-7l) be readily understood by those skilled in the art.

In the accompanying drawings, Fig. 1 is a horizontal section through the bracket-arm standard of a buttonhole sewing machine embodying the invention, showing the Work-clamp and machine bed in plan, Fig.V 2 is a bottom plan view of the work-clamp. Fig. 3 is a disassembled perspective View of one of the lower work-clamp plates and its inset section. Fig. e is a longitudinal vertical section through the machine with the work-clamp open and the buttonhole-cutter in retracted position, and Fig. 5 is a similar View with the clamp closed and the buttonhole-cutter in advanced or buttonhole cutting position. This figure also shows the lower inset sections of the work-clamp plates lifted to clear the needle-throat member which is tilted out of the way by the advance of the buttonhole-cutter.

The frame of the machine includes the usual bed 1 and bracket-arm standard 2. The stitch- 75 forming mechanism includes the usual reciprocating needle 3 which cooperates with the usual under-thread mechanism mounted on the turret 4 which also carries the usum needle-.throat member 5 which engages the under surface of 80 the Work exposed by the aperture 6 in the lower work-clamp sections 7, 7, which are set into the lower work-engaging and -supporting plates 8, 8 carried as usual by the cross-slide plate 9 and longitudinal slide-frame 1i); the work-clamp, ex- 85 cept for the inset sections 7, 7, and the means for tilting them, being constructed substantially in accordance with the disclosure of the Allen patents hereinblefore referred to. The workclamp also includes the upper clamp-feet 11 car- 90 ried by the usual clamp-arms 12 which are pivotally mounted at 15, Fig. 4, on their respective lower supporting plates 8 and are depressed to grip the work by the usual clamp-closing cams 16. The arms 12 are somewhat springy so that 95 they resiliently grip the work when depressed or closed by the cams 16.

The machine is `equipped with suitable button-hole-cutting mechanism, preferably that disclosed in my copending application, Serial No. 578,967,i filed herewith. Such a buttonholecutting mechanism comprises a lower cutter-lever 17 formed with a die 18 and an upper cutterlever 19 slidably carrying a punch 20 which mates with the die 18. The cutter-levers 17 and 19 105 are pivotally carried at 21 by the usual travelling fulcrum-block 22 which is slidable longitudinally of the bed 1 and has a rearward extension 23 connected by the link 24 to the cutter-advancing and -retracting cam 25 on the one-revolution 110 the advancing buttonhole cutter-levers.

cutter-shaft 26. The cutter-shaft also carries the cutter-closing cams 27, 28 which engage, respectively, the levers 17 and 19 and spread the rear ends of such levers, thereby forcing the forward ends of said levers together and causing the punch 2O to enter the die 18. The punch 20 is connected by the compound levers 29, 30 and the link 31 to the lower cutter-lever 17, so that a separation of the rear ends of the cutter-levers not only forces the forward ends of such levers toward each other, but also causes the punch 20 to slide in the front end of its carrier-lever 19 and be forced suddenly into the die, as explained in said copending application. When the cutter-levers are advanced to cut the 'buttonhola the needle-throat member 5 is displaced or tilted forwardly about its pivotal support 5 on the turret 4, as shown in Fig. 5. Such a tilting throat-member is well known and is shown, for example, in the Allen Patent No. 1,650,588, of Nov. 29, 1927.

Before the needle-throat member 5 is tilted forwardly, however, it is necessary to lift the inset lower clamp-sections 7, 7 to raise the aperture 6 above the level of the head of the needlethroat member 5. To this end the sections 7 are each formed at their rearward ends with a rounded bead 32 which is engaged by the groove 33, Fig. 3, of a corresponding hold-down block 34 screwed to the respective main work-supporting plate 8. The auxiliary lower clamp-sections or inset plates 7 are provided at their forward ends with depending lugs 35 having the lower forward corners beveled as shown at 36 for engagement by the beveled edge 37 of the transverse lever 38 fulcrumed at 39 below and carried by the cross-slide plate 9 and partially supported by the guide-bracket 40 screwed to the crossslide plate 9. l

The lever 38 has a screw-and-slot connection 41 with a link 42 which is connected to the toothed rack 43 slide-.bly mounted in a way 44 in the bed 1. This rack 43 is connected by the gear 45 to a rack 46 formed on the travelling fulcrum-block 22 which carries the buttonhole cutter-levers 17 and 19. The gear 45 is pivoted on the bed 1.

When the cutter-levers are in retracted position, Fig. 4, the beveled edge 37 of the lever 38 is in front of the beveled edges 36 of the lugs 35 and the needle-throat member 5 is in sewing position in the aperture 6 of the lower auxiliary clamp-sections 7, 7, as shown in Fig. 1.

When the cutter-levers are advanced to cut the buttonhole, the bar 43 is retracted by the action of the rack 45 and gear 45. The lever 38 is therefore swung to carry its beveled edge 37 against the beveled edges 36 of the lugs 35, deecting or wedging the latter upwardly and thereby lifting the lower inset clamp-sections '7, 7 about their rear ends as hinges as shown in Fig. 5. This lift of the inset clamp-sections '7, elevates the aperture 6 so that the needle-throat member 5 may be tilted about its fulcrum 5 by The vpivotal axes of the hinge points 32 of the inset clamp-sections '7, 'l are horizontal and preferably parallel to the respective pivotal axes 15 of the upper clamp-arms 12, so that the sections 7, '7 are raised and lowered, as are the clamp-feet 11. Upon the retraction of the buitonhole cutter-levers, the lever 38 is restored to the position shown in Fig. 1 and the inset clamp-sections '7 are returned to their horizontal positions upon the main lower work-supporting plates 8. By referring to Fig. 3, it will be observed that the clampplates 8 are formed with recessed seats 8 for the inset sections 7; the frontends of the latter being yieldingly retained in such seats by the thin leaf-springs 8'.

It will be understood that the auxiliary lower clamp-sections are lifted against the yielding pressures of the closed upper clamp-feet l1 and clamp-arms 12, without disturbing the main lower work-supporting plates 8.

Having thus set forth the nature of the invention, what l claim herein is:-

1. In a buttonhole sewing machine, a bed, a main lower work-engaging and -supporting plate mounted for movement over said bed, an upper clamp-foot mounted on said work-engaging and -supporting plate, a lower work-clamp section opposed to said clamp-foot and carried by said work-engaging and -supporting plate, and means for lifting said lower work-clamp section relative to said work-engaging and -supporting plate.

2. In a work-clamp for buttonhole sewing machines, a main lower work-engaging and -supporting plate having an inset lower clamp-section, an upper clamp-foot opposed to said clampsection, a clamp-arm carrying said clamp-foot and fulcrumed on said main lower plate, and means for lifting said inset clamp-section relative to said main lower plate.

3. In a buttonhole sewing machine, a workclamp having a main lower work-engaging and -s'upporting plate, opposed upper and lower clamp-members fulcrnmed on said plate, means for closing the upper clamp-member upon the work between said clamp-members, and means for lifting said lower clamp-member about its fulcrum while the upper clamp-member is in closed position.

4. A work-clamp for buttonhole sewing machines having a main lower work-engaging and -supporting plate, and opposed upper and lower work-clamping elements independently fulcrumed on said plate to swing about parallel axes.

5. 1n a buttonhole sewing machine, stitchforming mechanism including a reciprocating needle and a laterally shiftable needle-throat member, a work-clamp including lower clampsections apertured to expose an area of work to be stitched and admit said needle-throat member, upper clamp-feet opposed to said lower clamp-sections, a buttonhole-cutter, mechanism for advancing the buttonhole-cutter from a retracted position to cutting position while the work-clamp is held laterally stationary in sewing position, and means for lifting said lower clampsections clear of said needle-throat member, without lateral movement of said clamp-sections, to permit of a lateral shift of the needle-throat member to clear the way for the advancing buttonhole-cutter.

6. A work-clamp for buttonhole sewing machines having, a main lower Work-engaging and -supporting plate, a lower clamp-plate hinged to said main plate for rising and falling movements,

and an upper clamp-foot carried by said main plate independently of said lower clamp-plate.

7. A work-clamp for buttonhole sewing machines having main lower work-engaging and -supporting plates, upper clamp-arms fulcrumed on said plates, upper clamp-feet carried by said arms, said lower plates having inset lower clamp- ALFRED R. WOOD. 

